Two-part axial spacer for transformer windings



Patented Dec. 16, 1952 TWO-PART AXIAL SPACER FOR TRANSFORMER WINDINGSOliver M. Olivier, McKees Rocks, Pa., assigner to Allis-ChalmersManufacturing Company, M-ilwaukee, Wis., a corporation of DelawareApplication May 16, 1949, Serial No. 93,468

4 Claims.

This invention relates in general to stationary 'induction apparatus andparticularly to spacers for positioning the coils of the windings oftransformers and other induction apparatus.

In the prior art, coaxial windings of induction apparatus have beenspaced from one another and from insulation barriers by the use ofnarrow pressboard strips or sticks. In this manner uniform annularspaces are formed between stacks of windings and between windingsv andbarriers, and the stacks of windings are held in position. However,these spacer strips'or sticks are diicult to insert after the windingsare assembled, and the spacers may be inserted improperly. They maybecome displaced or may shift from proper position, and as a result, thecoils of the windings may become displaced.

In transformers or reactors where one of the windings comprises a stackof disk type coils, 'it is diiiicult to insert spacer strips or sticksbetween the stack of coils and the barrierwhich is next to `the stack ofcoils. Entry of the sticks is obstructed by the edges of individual diskcoils in the stack which edges protrude slightly and irregularly intothe space between the coils and `the barriers. When assembling thesewindings, layers of disk coils are superposed with radial spacersbetween the layers to provide space so that insulating fluid cancirculate between layers. Each of the coils has an edge on the innerperiphery of the stack and another on the outer periphery, and `it isnot feasible' to perfectly align these edges when one coil is placedover another with radial spacers therebetween. As a result neitherthe'inner nor the outer peripheral surfaces of the' windings areperfectly smooth.

' Means 'have been suggested to guide the entry of the spacer stickswhich are inserted between the stack of winding and the barriers.However, the prior art does not suggest how to provide proper and easyentry of the spacer sticks. The

.diiliculties resulting because of edges of coils or of radial vspacersprotruding unevenly from the stack has not been avoided in the priorart. The protruding portions of radial spacers may become torn anddisplaced; the insulation on the disk coils may become torn, and thespacer sticks may be damaged.

It is very important that twisting or shifting movement of the stack ofdisk coils with respect to the other windings or insulating barriers inelectric induction apparatus be completely avoided. Movement may resultwhile the apparatus is in transit or under conditions of energizationand luse when there are high stresses on the windings.

vinsulation barrier and other windings.

2 Therefore it isnecessary to firmly hold the stack of coils in positionand also important that the stack be perfectly aligned with respect tothe Any misalignment or displacement of the coils with respect to theinsulation barriers or other parts 'of the structure of the apparatuswill result in unnecessary `stresses in the apparatus when it isenergized and used.

To assure the proper alignment Aof the coils 'of the stack and also toavoid the possibility of twisting or shifting of the coils in transit orwhen excited for use, the vertical spacing sticks between a stack ofvcoils and va barrier should be slightly lgreater in thickness than thewidth of the annular cylindrical space between the stack of coils andthe barrier. The oversized spacing stick can be inserted in the spacebetween the coils and barrier, because of the resilience of the coils.The coils are thereby snugly positioned. However, since the cylindricalspace between the coils and barrier is not wider than the spacer stripto be inserted therebetween, it is necessary to have means by which thestrip can be inserted without being obstructed by the uneven orprotruding edges of coils or radialspacers between layers of coils. Thepossibility of not inserting the stick properly and vertically must beavoided.

The disadvantages 'of the prior art have been avoided by the presentinvention. One of the objects 'of the invention is to provide animproved means for spacing a stack of disk coils rfrom other windings orfrom an insulation barrier in an electric induction apparatus.

Another object of the invention is -to provide improved means by whichvertical spacers may be inserted between a stack of coils and aninsulation barrier in electric induction apparatus.

Still another object of the applicants invention is to provide improvedmeans for firmly and securely fixing windings in electrical inductionapparatus.

These and other objects of the invention which will hereinafter becomeapparent are accomplished by means of a spacer for use in electricinduction apparatus such as above referred to, wherein an element of thespacer can be anchored in position with respect to the windings and thebarriers and anotherelement of the spacer can be inserted with one sidebearing on the surface of the barrier and the opposite side bearing on asurface of the anchored element thereby causing forces to be exerted onthe stack ofA coils to firmly, snugly and properly position the 'stackof coils.

In the drawing:

Fig. 1 is a view in longitudinal cross section of part of a core typetransformer provided with spacers built in accordance with the presentinvention;

Fig. 2 is a partial cross sectional view of the transformer shown inFig. 1 taken along line II-II of Fig. l;

Fig. 3 is an enlarged view in elevation of the spacer shown in Fig. 1and of a portion of the adjacent barrier;

Fig. 4 is a plan View of the spacer and barrier portion shown in Fig. 3;

Fig. 5 is a View in elevation of the grooved strip element of the spacershown in Fig. 3:

Fig. 6 is a side view of the grooved strip shown in Fig. 5; and

Fig. '1 is a plan view of the grooved strip shown in Fig. 5.

The transformer, of which only a portion is shown in Figs. 1 and 2,includes a magnetic steel core with high and low Voltage windingssurrounding a leg of the core.

The low voltage winding I2, I3 is cylindrical in form. The two sectionsI2, I3 of low voltage winding are separated from each other by spacersI4 andare insulated from the laminated iron leg member` l5 of the coreby the wound insula.- tion or foundation member I5. In the structureshown, wooden members I1 are used to space section I2 of the low voltagewinding from the core steel.

A stack of high voltage windings of the disk type are shown. Radialspacers 2| are inserted between the layers of the disk coils separatingthe coils from each other thereby insuring the circulation of air or oilto the individual coils in the winding stack.

Cylindrical insulation barriers 24, 25, are positioned between lowvoltage Winding I2, I3 and the stack of high voltage coils 20 forinsulating purposes. The insulation barriers are spaced from each otherand from the low voltage windings by spacers 21 which arecircumferentially spaced from each other and are radially7 aligned withspacers 2|.

In building transformers such as the one represented in Figs. l and 2the sections of low voltage winding and the insulation barriers are nottoo diflicult to place in position as both the low voltage windings andthe barriers all are of cylindrical form. However, the high voltageWinding, which is a stack of disk coils 2U, is not so easy to positionwith respect to the insulation barriers and the other elements of thetransformer. The high voltage stack must be firmly and snugly held andproperly positioned with respect to the other elements of thetransformer. And since the high voltage stack is assembled bysuperposing one disk coil 2U over another with radial spacers 2ltherebetween, the surface 3| defined by the inner edges of theseindividual disk coils, which surface will be referred to as the innerperipheral surface of the high voltage stack, is irregular compared withthe smooth surfaces of the barriers and of the low voltage Winding.

Also, the stack of disk coils is usually assembled after the other partsof the structure are assembled, and it is desirable to space the stackkfrom the nearest barrier after the complete high voltage stack isassembled. The present invention provides a novel and efcient means forspacing the entire stack of high voltage coils from the nearest barrierafter assembly. This will be hereinafter described in full. This spacingmeans is referred to by the reference numeral 33.

In the transformer shown the high voltage stack en the low voltagewindings are supported and insulated from the yoke members 34, 35 of thecore and from the heavy reinforcing channel members 36, 31 which areover the yoke members, by built-up insulation 38, 39 at each end of thewinding assembly. In addition, insulation washers tl and spacers 42, 43increase the spacing between the high voltage stack and the yokes andchannel members. Standard insulation is intended to be represented bynumerals 38 to 43. This includes yoke pads, washers, washer fillers,spacers and built-up blocks.

An electrostatic plate 44 may be placed next to the line end of thestack of coils in order to provide distribution of impulse voltagesacross the iirst coil.

The complete winding assembly, including the high voltage and lowVoltage windings with the insulation and padding, is clamped between thechannel members 36, 31 by strong tie rodstnot shown). Also, bolts (notshown) through the channel members are used to clamp the core and themechanical parts. Clamping tie rods and bolts are employed inconventional manner for this type transformer.

The spacing means represented by numeral 33 is used for snugly xing thestack of high yvoltage disk coils 2D in place and uniformly spacing thestack from the insulation barrier.

The spacer means consists of a plurality of spacer assembliescircumferentially spaced about barrier 26. Each assembly is made of twoparts. One part d5 is a grooved spacer element of pressboard or similarlaminated cellulosicl insulating material. The other part 45 of thespacer means is a drive stick made of laminated synthetic resin or otherinsulating material. The drive stick 46 is driven between the groovedstrip and the barrier, and thus tightens and positions the stack.

In Figs. 3 to 7 one of the spacers of means 33 is shown. Pressboard orother similar insulating material is out to the rectangular shape of thestrip outlined in Fig. 5. Then the ycentral portion 41 of the strip isscored lengthwise thereof along lines 4g and i3 by a saw or knife cut.The pressboard is scored only through part of the thickness of the stripand then the material between lines 43 and 4S is removed from the strip.Numeral 6i) represents the depth of the saw` cut which will usuallyextend to a slightly vgreater depth than the thickness of the layers oflaminations which are removed. Thus one side of Vthe strip member 45 hasa rectangular recess 5I 'formed therein having sides along lines ,48 and49 and a base therebetween along line 52. The opposite side 53 of thestrip 45 has a flat surface. The grooved spacer strip with only thelongitudinally extending portion removed may be satisfactory for use inmany transformers. However, at times it may be desirable and importantthat the end portions 55, 5G of the grooved strips be` flat. In suchinstances, the strip member 45 is scored along lines 58, 59 crosswise ofthe direction of the lengthwise groove. The pressboard material betweenthe scored line 58 andthe end 52 and between line 53 and the end 6I isremoved to a depth not greater than the depth of scored lines 58, 5S sothat the end portions 55, `55 are dat. Thus the ends of these stripswhich are bent along lines S4, and extend radially below and above thestack of disk coils have a substantially flat surface, and 'the5stripils`iirmly and tightly heldinpesition by't-hest-ac'k.A

A "similar spacerstrip vcan be ina-de ylother methods, such as4bybuilding up the-laf ations tothe iinal f'c-rm indicated'in Figs. 5,'f6 and? j "In-the assembly of a transformer such 'asthe 'one shown,when the lowvolta'ge'winding I2, 51'3 and the insulation barriers 24,2-5, v2li are in place surrounding the core member l5, several fof thegroeved strip `"elemer'i'its-45 are circumferentially spaced from oneanother around the insulation barrier 26, withthe 'portion intermediatethe end portions 55, 56 extending in a lengthwise direction parallel tothe axis. of the barrier '2.6. The end portion 55 is bent at an angle 90to the intermediate portion along line .65 and the end portion 55extends over the yoke padding 3.9.. The insulation washers 4l andspacers "43 .aregpiaced overthe end portions 55 of theseveral groovedstrip elements. Radial spacersZl are circumferentially spaced from eachother'on 'topof tliespacer 43. rIhen the disk coils2'0"are Vplaced aboutthe core member 15, the low 'voltage winding I2, I3 and barriers 24, 25,26. The first disk coil 20 rests upon the radial spacers 2|, and thegrooved strip elements are thereby anchored in position. The entirestack of disk coils is assembled. Spacers 42 and washers 40 are placedover the stack, and then end portions 56 of the strips are bent alongline 64 at an angle of 90 to the intermediate portion of the strip sothat the end portions 56 extend over the disk coils and the insulationwashers and spacers.

After the high voltage stack is assembled a driving stick preferablywith at least one end 61 tapered is driven between the barrier 25 andeach grooved spacer element 45. The stick 46 is approximately as wide asthe width of the groove. The thickness of the stick is greater than thedepth of the groove. Therefore, when the stick is driven between thebarrier and the strip, the stick forces the strip away from the barrier,thereby spacing the stack of disk coils from the barrier. Entry of .thestick after assembly o-f the stack of coils without damage to the stickor coil insulation is assured by the use of the grooved strip. Thedriving stick is retained in the groove of the strip while one side 69of the driving stick bears against the comparatively smooth surface ofthe strip and the other side 68 of the driving stick bears against thesmooth outer surface of the barrier.

The spacer means including the driving stick and the grooved strip canbe slightly greater in thickness than the width of the space between thebarrier and stack before the stick is inserted therebetween. Thus, whenthe stick is inserted, the width of the space is slightly .increasedbecause of the resilience of the disk type coils of the high voltagewinding. In this manner the stack of disk coils is firmly and snuglypositioned. After the spacer is properly positioned, the padding 38 isplaced in position over the winding assembly.

The yoke member 34 and channel member 36 are then put in position. Rodsand bolts are added to the structure between channel members clampingthe entire unit in the usual manner to give str ong mechanical supportto the windings and coils.

Although but one embodi-ment of the present invention has beenillustrated and described, it will be understood by those skilled in theart that various changes and modifications may be made therein withoutdeparting from the spirit :of the' invention for from the l'scope forthe/ep pended claims. f It is lclaimed and-desired to lsecu-rie byLetters Patenti i 21.. An electric induction apparatus including' .acy-lindrical insulation barrier, .a .stack of fdisk coilssuiround'ingsaid barrier-and radially spaced fromlsaid barrier to form an annular:cylindrical lpassageway between said barrier and saidstack of coils,means for spacing said coils from .'said barrier, said means including`spacers extending in a'jdirection vparallel to the longitudinal axis ofsaid barrier, said spacers being circumferentially spaced from eachother in said passageway, each of said spacers comprising a strip ofinsulating :material having a fla-t side bearing against the edges ofsaid disk coils and extending frombne endl of said stack to the otherend of said stack. the :opposite side of said strip having a recessextending lengthwise parallel to theaxis 'o'said stack, the end portionsof said strip being bent and extended over the ends of said stacksothaft said strip 'i's `firmly held in positionrelative "to said stack,and a stick of insulating material having a thickness greater than thedepth of said recess inserted in said recess and extending.

at least from one end of said stack to the other end thereof withopposite sides of said stick bearing against the surface of said barrierand against the base of said recess.

2. An electric induction apparatus including a cylindrical insulatingbarrier, a plurality of disk coils constituting a winding surroundingsaid barrier, said winding having resilience to forces acting radiallyon the edges of said coils, said winding being radially spaced from saidbarrier to define an annular cylindrical passageway between said barrierand said winding, and means for snugly holding said winding with respectto said barrier comprising a plurality of spacers circumferentiallyspaced in said passageway, one of said spacers comprising a strip ofinsulating material extending lengthwise at least from one end of saidwinding to the other end thereof, the end portions of said strip beingbent and extending over the ends of said stack so that said strip isfirmly held in positionrelative to said stack, a first side of saidstrip facing said barrier and having a groove therein extendinglengthwise of said strip, the opposite side of said strip bearingagainst said winding, and a stick of insulating material insertedbetween and abutting against said barrier and said strip with said stickpartly retained in said groove, said one of said spacers having a radialthickness slightly greater than the radial distance between said windingand said barrier, whereby insertion of said stick into said groovecauses local radial deformation of said winding to maintain said one ofsaid spacers in place by the resilience of said winding.

3. An electric induction apparatus including a winding having resilienceto forces acting radially from the axis thereof, an insulating barriercoaxially disposed with respect to said winding, and means firmlypositioning said winding in radial spaced relation with respect to saidbarrier by slightly increasing the distance between local areas of theadjacent peripheral surfaces of said winding and of said barrier, saidmeans including a spacer comprising a strip of insulating materialinserted between said barrier and said winding and extending in adirection parallel to the longitudinal axis of said winding from atleastone end of said winding to the other end thereof, said strip having alongitudinally extending groove in a side thereof facing said barrier,and an insulating stick retainedin said groove and bearing on said stripand said barrier, said spacer having a radial thickness slightly greaterthan the radial distance between said winding and said barrier, wherebyinsertion of said stick into said groove causes local radial deformationof said winding to maintain said spacer in place by the resilience ofsaid winding.

4. An electric induction apparatus including a cylindrical insulatingbarrier, a plurality of superposed disk coils surrounding said barrier,said coils being formed of conductive material spirally Wound layer overlayer and having resilience to forces acting radially on the edges ofsaid coils, and spacing means for snugly holding said disk coils withrespect to said barrier, said means including a strip of insulatingmaterial having one side bearing against the edges of said coils andhaving a recess in the opposite side of said strip extending parallel tothe longitudinal axis of said barrier, and an insulating stick insertedin said REFERENCES CITED The following references are of record in thefile of this patent:

v UNITED STATES PATENTS Number Name Date 1,426,940 Wulff Aug. 22, 19221,938,421 Gilbert Dec, 5, 1933 1,943,597 Gilmer Jan. 16, 1934 2,081,754Lockhart May 25, 1937 2,116,404 Montsinger May 3, 1938

